org.apache.logging.log4j.util.ServiceLoaderUtil Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to you under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.logging.log4j.util;
import static java.util.Objects.requireNonNull;
import edu.umd.cs.findbugs.annotations.Nullable;
import java.util.HashSet;
import java.util.Iterator;
import java.util.ServiceConfigurationError;
import java.util.ServiceLoader;
import java.util.Set;
import java.util.Spliterators;
import java.util.function.Consumer;
import java.util.stream.Stream;
import java.util.stream.StreamSupport;
/**
* Handles {@link ServiceLoader} lookups with better error handling.
*/
@InternalApi
public final class ServiceLoaderUtil {
private static final int MAX_BROKEN_SERVICES = 8;
private ServiceLoaderUtil() {}
public static Stream safeStream(final Class type, @Nullable final ClassLoader classLoader) {
requireNonNull(type, "type");
final ClassLoader effectiveLoader = classLoader != null ? classLoader : type.getClassLoader();
final ServiceLoader serviceLoader = ServiceLoader.load(type, effectiveLoader);
return safeStream(serviceLoader);
}
public static Stream safeStream(final ServiceLoader serviceLoader) {
requireNonNull(serviceLoader, "serviceLoader");
final Set> classes = new HashSet<>();
return StreamSupport.stream(new ServiceLoaderSpliterator<>(serviceLoader), false)
// only the first occurrence of a class
.filter(service -> classes.add(service.getClass()));
}
private static class ServiceLoaderSpliterator extends Spliterators.AbstractSpliterator {
private final Iterator serviceIterator;
private final String serviceName;
private ServiceLoaderSpliterator(final ServiceLoader serviceLoader) {
super(Long.MAX_VALUE, ORDERED);
serviceIterator = serviceLoader.iterator();
serviceName = serviceLoader.toString();
}
@Override
public boolean tryAdvance(final Consumer action) {
int i = MAX_BROKEN_SERVICES;
while (i-- > 0) {
try {
if (serviceIterator.hasNext()) {
action.accept(serviceIterator.next());
return true;
}
} catch (final ServiceConfigurationError | LinkageError e) {
LowLevelLogUtil.logException("Unable to load implementation for " + serviceName, e);
} catch (final Throwable e) {
LowLevelLogUtil.logException(
"Unexpected exception while loading implementation for " + serviceName, e);
throw e;
}
}
return false;
}
}
}